1. Field of the Invention
The present invention relates to a heat pump type air-conditioner and, more particularly, to a system and method for detecting a clogged state of a pipe of the heat pump type multi-air conditioner capable of detecting a clogged state of a pipe of a heat pump type multi-air conditioner including a plurality of outdoor units and a plurality of indoor units.
2. Description of the Background Art
An air-conditioner is a device for controlling a temperature, humidity, an airflow and cleanliness of a room to make an agreeable indoor environment. According to the construction of included elements, the air-conditioner is divided into an integrated type air-conditioner of which an indoor unit and an outdoor unit are all accommodated in a single case and a separated type air-conditioner of which a compressor and a condenser are used as an outdoor unit and an evaporator is used as an indoor unit, separately.
Also, there is an air-conditioning/heating combined air-conditioner which can selectively perform a cooling and heating operation by switching a fluid path of a refrigerant by using a four-way valve, and recently, a multi-air conditioner having a plurality of indoor units which can perform cooling or heating in each indoor space is increasingly used. As for the multi-air conditioner, in order to suitably cope with an operation load of the plurality of indoor units, a plurality of outdoor units each having a compressor are used to be connected in parallel with the plurality of indoor units.
A structure and operation of a heat pump type multi-air conditioner including a plurality of outdoor units and a plurality of indoor units in accordance with a background art will now be described with reference to FIG. 1.
FIG. 1 illustrates the construction of an outdoor unit of a heat pump type multi-air conditioner in accordance with a background art.
As shown in FIG. 1, a plurality of outdoor units 11a˜11n include a pair of first and second compressors 13a and 13b for compressing a refrigerant; a four-way valve 21 for switching a flow path of the refrigerant; an outdoor heat exchanger 23 for exchanging heat absorbed by the refrigerant with outdoor air; and a common accumulator 25 for providing a gaseous refrigerant to the first and second compressors 13a and 13b, respectively.
A discharge pipe 15 for discharging the refrigerant is provided at an upper portion of the first and second compressors 13a and 13b, respectively, and a suction pipe 17 connected with the accumulator 25 is coupled with a lower portion of each compressor and supplies the refrigerant to the compressors.
An oil-balancing pipe 19 is connected between the first and second compressors 13a and 13b so that oil inside the compressors 13a and 13b can flow to each other.
An oil separator 31 and a check valve 33 are provided at each discharge side of the first and second compressors 13a and 13b, and an oil return flow path 35 for returning oil to the suction side of each compressor is connected with the oil separator 31.
The four-way valve 21 for switching the flow path of the refrigerant is provided at a lower side of the check valve 33.
One port of the four-way valve 21 is connected with the outdoor heat exchanger 23, another port of the four-way valve 21 is connected with the common accumulator 25, and still another port of the four-way valve 21 is connected with one end of a connection pipe 41 connected with the side of an indoor unit.
A receiver 37 is provided at one side of the outdoor heat exchanger 23 according to a direction of a flow of the refrigerant, and service valves 43a and 43b are provided at one side of the receiver 37 and one side of the connection pipe 41.
The service valves 43a and 43b are connected with main refrigerant pipes 45 which connects the outdoor units 11a˜11n. 
As shown in FIG. 2, the background art heat pump type multi-air conditioner connects the plurality of outdoor units 11a˜11n and the plurality of indoor units.
FIG. 2 illustrates a state of connection between the plurality of outdoor units and the plurality of indoor units.
The plurality of outdoor units 11a˜11n and the plurality of indoor units are connected through a communication line, and one of the plurality of outdoor units 11a˜11n is operated as a central controller controls cooling/heating air-conditioning of the other remaining outdoor units and the plurality of indoor units.
However, the background art heat pump type multi-air conditioner has the following problems.
That is, since the plurality of outdoor units and the plurality of indoor units are to be connected to be used, a diameter of the pipe is increased, and due to an installation condition that the pipe is lengthened, more parts of the pipe are to be welded, increasing a probability that debris exists inside the pipe as shown in FIG. 3. In this case, if debris is collected on a strainer inside the pipe, it would clog the pipe, preventing a normal operation of the multi-air conditioner to degrade an air-conditioning force or heating force.